WASHINGTON — The Food and Drug Administration has approved a stronger, single-ingredient version of the painkiller hydrocodone, the widely-abused prescription medicine for chronic pain.

The agency said it approved the pill Zohydro for patients with pain that requires “daily, around-the-clock, long-term treatment” that cannot be addressed with other drugs.

Hydrocodone is currently sold in combination pills like Vicodin to treat pain from injuries, surgery, arthritis, migraines and other ailments. The new drug from Zogenix is the first pure, non-combination form of the drug approved in the U.S.

The approval comes as a surprise since the agency’s own panel of outside advisers gave the drug an overwhelmingly negative review last year. The agency’s panel of pain specialists voted 11-2, with one abstention, against approving the drug last December, questioning the need for a new form of one of most widely-abused prescription painkillers in U.S.

The FDA announcement also comes just one day after the agency said it would support stronger restrictions on combination drugs containing hydrocodone, including Vicodin and dozens of other generic formulations.

The drugs currently available mix hydrocodone with non-addictive pain relievers like aspirin and acetaminophen. For decades these drugs have been subject to less rigorous prescribing limits than other prescription painkillers like oxycodone.

Late Thursday, the FDA said it would recommend moving hydrocodone drugs from the schedule III class to the schedule II class of medications, a move that will limit the number of refills patients can receive and how many health professionals can prescribe the drugs.

The Drug Enforcement Administration had first asked the agency to take that step a decade ago, and lawmakers and safety advocates had increased their pressure on the agency in recent years.

In 2011, U.S. doctors wrote more than 131 million prescriptions for hydrocodone, making it the most prescribed drug in the country, according to government figures. Hydrocodone pills also consistently rank among most-abused medicines in the U.S., according to the DEA.

The drug belongs to a family of medicines known as opiates or opioids because they are chemically similar to opium. They include morphine, heroin, oxycodone, codeine and methadone.

Shares of San Diego-based Zogenix Inc. jumped in trading Friday, climbing 85 cents, or 37.9 percent, to $3.09. Earlier shares set a 52-week high of $3.45.